[1] Univ North Carolina Chapel Hill, Sch Med, Div Oncol, Campus Box 7305, Chapel Hill, NC 27599 USA
[2] Univ North Carolina Chapel Hill, Lineberger Comprehens Canc Ctr, Chapel Hill, NC 27599 USA
[3] Univ North Carolina Chapel Hill, Gilling Sch Global Publ Hlth, Chapel Hill, NC USA
[4] Duke Univ, Sch Med, Dept Populat Hlth Sci, Durham, NC USA